TY - CONF A1 - Herbst, Tristan A1 - Rübner, Katrin A1 - Meng, Birgit A1 - Hauer, B. T1 - Sustainable evaluation - concept to assess the applicability of secondary aggregates in concrete N2 - Nowadays there are several applications of mineral recycling materials and residues. At present an assessment method for the use of secondary raw materials, which considers sustainability aspects, does not exist. In the framework of the German DAfStb/BMBF research project “Sustainable Building with Concrete” an assessment concept was developed. It includes the following four assessment steps: I. Basic considerations, II. Advantages for sustainable construction, III. Alternative paths for application, and IV. Sensitivity analysis. The concept was developed on the basis of recycled concrete aggregates, which are already used according to German standards. Afterwards, it was applied and verified by the evaluation of the utilisation of municipal solid waste incinerator bottom ashes (referred to MSWI bottom ashes). T2 - 2011 Helsinki world sustainable building conference CY - Helsinki, Finland DA - 18.10.2011 KW - Sustainable building KW - Sustainability aspects KW - Secondary materials KW - Secondary aggregates in concrete KW - Energy and material resources KW - Assessment concept PY - 2011 SN - 978-951-758-534-7 SN - 0356-9403 SP - 1 EP - 8 AN - OPUS4-24781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Birgit A1 - Müller, Urs A1 - Fontana, Patrick ED - Rogge, A. ED - Meng, B. T1 - Neue Erkenntnisse und Analysemethoden zum Phasenbestand und Gefüge des Zementsteins T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Baustoffe KW - Zement KW - Mörtel KW - Mineralogische Zusammensetzung PY - 2011 SN - 978-3-9814281-0-0 SP - 11 EP - 17 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25198 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Voland, Katja A1 - Weise, Frank A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Untersuchung des Einflusses der Gefügedichte von Betonen auf die AKR mit neuartiger Prüftechnik T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Alkali-Kieselsäure-Reaktion KW - Nebelkammerlagerung bei 40° C KW - 60° C-Betonversuch KW - Dehnungsmessung KW - Schallemissionsanalyse KW - Ultraschallgeschwindigkeit KW - mu-3D-CT PY - 2011 SN - 978-3-9814281-0-0 SP - 86 EP - 95 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25199 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rübner, Katrin A1 - Herbst, Tristan A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Ressourcenschonung durch Reststoffverwertung im Betonbau T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Germany DA - 07.11.2011 PY - 2011 SN - 978-3-9814281-0-0 SP - 283 EP - 294 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-25175 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Urs A1 - Meng, Birgit A1 - Bürgisser, Philip ED - Rogge, A. ED - Meng, B. T1 - Das natürliche Puzzolan 'Rheinischer Trass' und dessen Einfluss auf eine Alkali-Kieselsäure-Reaktion (AKR) in Beton T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 PY - 2011 SN - 978-3-9814281-0-0 SP - 141 EP - 150 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25187 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pistol, Klaus A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Zur Wirkungsweise von Polypropylen-Fasern in brandbeanspruchten Hochleistungsbetonen T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Polypropylen-Fasern KW - Hochfester Beton KW - Schallemissionsanalyse KW - Röntgen 3D-Computertomographie KW - Rasterelektronenmikroskopie PY - 2011 SN - 978-3-9814281-0-0 SP - 134 EP - 140 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25188 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krütt, Enno A1 - Weise, Frank A1 - Meng, Birgit T1 - Einfluss einer druckschwellinduzierten Degradation von Fahrbahndeckenbeton auf die schädigende AKR T1 - Influence of cyclic compressive loading induced degradation of road pavement concrete on harmful AAR N2 - In den letzten Jahren sind im deutschen Bundesautobahnnetz verstärkt Schäden an vor 2005 errichteten Betonfahrbahndecken aufgetreten, die mit einer Alkali-Kieselsäure-Reaktion (AKR) in Verbindung gebracht werden. Neben dem AKR-fördernden Einfluss von alkalihaltigen Taumitteln werden Fahrbahndecken zyklischen mechanischen Belastungen infolge des Verkehrs und Zwangsspannungen durch klimatische Einwirkungen ausgesetzt. Solche mechanischen Belastungen werden bisher in keinem AKR-Prüfverfahren berücksichtigt. Die zyklischen Belastungen können zu einer Degradation des Betongefüges führen, die ggf. einen AKR-fördernden Einfluss hat. Dieser Beitrag stellt Untersuchungen vor, die zur Beantwortung der Frage nach dem Einfluss einer zyklischen mechanischen Belastung auf den AKR-Schadensprozess beitragen. Dabei wird der Hypothese nachgegangen, dass die ermüdungsinduzierte Degradation zu einer Erhöhung des Stofftransports führt. Dieser hat einen Einfluss auf die AKR-Schadensentwicklung, da die Reaktionspartner zunächst zum Reaktionsort transportiert werden müssen. Daher wird angenommen, dass sich mit dem Stofftransport auch die AKR-Schädigung verstärkt. Es werden Betonproben aus typischen Fahrbahndeckenbetonen einer vorgeschalteten zyklischen Druckschwellbelastung ausgesetzt. Die Degradation infolge der Vorbelastung wird simultan mittels ZfP-Verfahren charakterisiert. Anschließend werden die Auswirkungen der zyklischen Vorschädigung auf den Stofftransport sowie auf die AKR vergleichend an Prüfkörpern ohne und mit Vorschädigung untersucht. Die Ergebnisse lassen den Schluss zu, dass die zyklische Vorschädigung sowohl den Stofftransport als auch die AKR fördert. N2 - In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces built before 2005, which can be attributed to the alkali-silica reaction (ASR). In addition to exposure to ASR-stimulating alkalirich deicing-agents, road surfaces are also subjected to cyclical mechanical loading resulting from traffic and induced stresses due to climatic impact. Such mechanical loadings are not considered in any of the previously developed ASR testing procedures. This cyclical loading could, however, lead to a degradation of the concrete microstructure and, in turn, stimulate the ASR-process. This article presents investigations that contribute to answering the question of whether a mechanically induced degradation influences the ASR-process. The hypothesis that the mechanically induced degradation leads to an increase in mass transport is examined. The mass transport is important for the ASR process because the reactants need to be transported to the reaction location before the reaction can take place. Therefore, it is assumed that increased mass Transport also leads to increased ASR damage. Concrete specimens made of typical pavement concretes are subjected to a predamaging cyclic compressive loading. The degradation is characterized simultaneously during the pre-damaging process using non-destructive testing (NDT) techniques. Then the effects of the cyclical pre-damage on the mass transport as well as on the ASR are determined by comparing results from test specimens with and without pre-damage. The results lead to the conclusion that the cyclical pre-damage increases both the mass transport and the ASR. KW - Stofftransport KW - Betonfahrbahndecken KW - AKR KW - Zyklische Belastung KW - Degradation PY - 2020 DO - https://doi.org/10.1002/best.202000017 SN - 0005-9900 VL - 115 IS - 10 SP - 779 EP - 788 PB - Wilhelm Ernst & Sohn CY - Berlin AN - OPUS4-51561 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Voigt, Marieke A1 - von Werder, Julia A1 - Meng, Birgit ED - Middendorf, B. ED - Fehling, E. T1 - Microstructure analysis of thermally treated ultra high performance concrete in the context of the durability performance N2 - Ultra high performance concrete (UHPC) is known for its high compressive strength of more than 150 MPa and its high durability. Thermal treatment at 90°C can accelerate the strength development so that the 28-days-strength can be achieved immediately after the treatment and an additional increase up to 30 % in some cases. The reason for the strength development is an accelerated hydration of the clinker minerals and an intensified pozzolanic reaction leading to a denser microstructure. In previous research inhomogeneities in form of a zonation after unprotected thermal treatment were observed and analysed in respect to changes in the microstructure. This zonation is defined by a different microstructure in the core compared to the outer zone in the matter of porosity, mineral phase composition and a significant change in the potassium and sulphur concentration of the zones is measurable. To isolate different transport mechanisms responsible for these element distributions UHPC samples were thermally treated at 90 °C and the microstructure was investigated under dry conditions and after immersion in water to investigate the influence of dehydration during and rehydration after the thermal treatment on the microstructure. Through durability testing via water absorption, water vapour diffusion, permeability testing and sulfuric acid resistance transport mechanisms like diffusion, migration, capillary suction are under investigation in correlation with the microstructure analysis. For the microstructure analysis measurements with µXRF, mercury intrusion porosity, XRD and SEM were conducted. T2 - HiPerMat 2020 CY - Kassel, Germany DA - 11.03.2020 KW - UHPC KW - Thermal treatment KW - Zonation KW - Transport mechanism KW - Durability PY - 2020 SN - 978-3-7376-0828-2 DO - https://doi.org/10.17170/kobra-202002271026 VL - 23 SP - 151 EP - 152 PB - Kassel University Press CY - Kassel AN - OPUS4-52373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voigt, Marieke A1 - von Werder, Julia A1 - Meng, Birgit T1 - Investigation of the zonation of thermally treated ultra high performance concrete N2 - Ultra high performance concrete (UHPC) is characterised by its high compressive strength of more than 120 MPa and its high durability. With thermal treatment at 90°C, hydration is accelerated and a strength comparable to the 28-day strength can be achieved immediately after the treatment. In applying Optimum process conditions, the strength can be even further increased by up to 30%. Previous Research showed that thermal treatment can lead to inhomogeneities in form of a visible zonation within the cross-section, if the UHPC is not protected sufficiently from desiccation. This led to the question, to what extent the related changes in mechanical properties, microstructure and phase composition are of relevance for the performance of the UHPC. First investigations of small specimens thermally treated without protection exhibited a decrease of compressive strength, indicating that the zonation aspect requires further research. In this study the zonation of UHPC treated thermally at 90°C is investigated after applying four different procedures of treatment and curing in comparison. The samples are characterized with respect to their chemistry, mineral composition and microstructure to allow an assessment on durability and strength development, with focus on potential depth dependent changes associated with the zonation. The measurements reveal the formation of a visible zonation in case of unprotected treatment, if followed by immersion in water. The compressive strength is not significantly impaired, but a decrease in bending strength gives reason for concern. Further results allow clear correlation with changes in pore structure, whereas the interpretation of relationships with phase distribution, degree of hydration, microchemistry is more complex and therefore, provides only partial clarification. KW - UHPC KW - Thermal treatment KW - Zonation KW - Desiccation KW - Microstructure KW - Durability PY - 2020 DO - https://doi.org/10.1016/j.conbuildmat.2020.119187 VL - 254 SP - 119187 PB - Elsevier Ltd. AN - OPUS4-50828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Birgit T1 - Possibilities for improving the properties of UHPC by means of thermal treatment N2 - A further improvement of the excellent properties of UHPC can be realized with thermal Treatment. Like for normal concrete, it accelerates the hardening and prevents shrinkage after the treatment. Additionally, an increase in strength can be achieved. Aim of this study was the optimisation of the thermal Treatment conditions of UHPC for very different Treatment methods; heat Treatment at 90 °C for unprotected and sealed samples, hot water bath at 90 °C and hydrothermal Treatment at 185 °C/1.1 MPa. The pre-storage time and the dwell time were systematically varied for each method to gain a higher strength. The compressive strength depends on the manner of Treatment at which higher water accessibility leads to higher strengths. The Phase composition changes considerably with different Treatment tempereatures. Finally, it can activate unhydrated binder components forming additional C-S-H, leading to higher strength. T2 - International Symposium on Ultra-High Perfomance Fibre-Reinforced Concrete UHPFRC 2017 CY - Montpellier, France DA - 02.10.2017 KW - Building Materials KW - Ultra-High Performance Concrete (UHPC) KW - Heat treatment KW - Autoclaving KW - X-ray diffraction (XRD) PY - 2017 AN - OPUS4-42570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rachmatulin, Natalia A1 - Gardei, André A1 - von Werder, Julia A1 - Meng, Birgit A1 - Süßmuth, J. A1 - Gerdes, A. A1 - Ballschuh, D. A1 - Seibt, H. T1 - Funktionalisierung von Polymerfasern - ein Beitrag der Tensidchemie für dauerhafte zementgebundene Werkstoffe N2 - Im Gegensatz zur Druckfestigkeit weisen zementgebundene Werkstoffe i. a. nur geringe Zugfestigkeiten auf. Ein Weg, Zugfestigkeiten zementgebundener Werkstoffe zu erhöhen und Rissbildung aufgrund von Zugspannungen zu verringern, besteht in der Einarbeitung von Fasern, die diese Spannungen aufnehmen. Häufig eingesetzt werden Stahlfasern, obwohl synthetische Polymerfasern leichter und meist beständiger gegenüber chemischen Angriffen und Korrosion sind. Die Polymerfasern zeigen allerdings meist einen deutlich schwächeren Haftverbund, was an der hydrophoben Faseroberfläche liegt. Um nun eine Anbindung der Fasern an die mineralische Matrix zu erreichen, müssen die Faseroberflächen modifiziert werden, ohne dass die mechanischen Eigenschaften negativ beeinflusst werden. Eine Herausforderung besteht somit in einer Oberflächenmodifikation durch eine schonende Behandlung der Fasern zur Erzeugung von anbindungsfähigen Gruppen. Durch eine Behandlung von modifizierten Fasern mit geeigneten Polymerlösungen werden die Oberflächeneigenschaften verändert und erlauben eine Anbindung an die Zementsteinmatrix. Der Einsatz von Tensiden als grenzflächenaktive Verbindungen ermöglicht in diesem Zusammenhang eine Vermittlung zwischen Polymeroberflächen und mineralischen Werkstoffen. T2 - HighTechMatBau CY - Berlin, Germany DA - 31.01.2018 KW - Zementgebundene Baustoffe KW - Lichtmikroskopie KW - Röntgen-3D-Computertomographie KW - Einzelfaserdurchzugsversuch KW - Windkanal KW - Fasermodifikation KW - Oberflächenfunktionalisierung KW - Grenzflächenaktive Verbindung PY - 2018 SN - 978-3-7388-0082-1 SP - 31 EP - 35 PB - Fraunhofer IRB Verlag CY - Stuttgart AN - OPUS4-44651 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rachmatulin, Natalia A1 - Gardei, André A1 - von Werder, Julia A1 - Meng, Birgit A1 - Süßmuth, J. A1 - Gerdes, A. T1 - Funktionalisierung von Polymerfasern - ein Beitrag der Tensidchemie für dauerhafte zementgebundene Werkstoffe N2 - Im Gegensatz zur Druckfestigkeit weisen zementgebundene Werkstoffe i. a. nur geringe Zugfestigkeiten auf. Ein Weg, Zugfestigkeiten zementgebundener Werkstoffe zu erhöhen und Rissbildung aufgrund von Zugspannungen zu verringern, besteht in der Einarbeitung von Fasern, die diese Spannungen aufnehmen. Häufig eingesetzt werden Stahlfasern, obwohl synthetische Polymerfasern leichter und meist beständiger gegenüber chemischen Angriffen und Korrosion sind. Die Polymerfasern zeigen allerdings meist einen deutlich schwächeren Haftverbund, was an der hydrophoben Faseroberfläche liegt. Um nun eine Anbindung der Fasern an die mineralische Matrix zu erreichen, müssen die Faseroberflächen modifiziert werden, ohne dass die mechanischen Eigenschaften negativ beeinflusst werden. Eine Herausforderung besteht somit in einer Oberflächenmodifikation durch eine schonende Behandlung der Fasern zur Erzeugung von anbindungsfähigen Gruppen. Durch eine Behandlung von modifizierten Fasern mit geeigneten Polymerlösungen werden die Oberflächeneigenschaften verändert und erlauben eine Anbindung an die Zementsteinmatrix. Der Einsatz von Tensiden als grenzflächenaktive Verbindungen ermöglicht in diesem Zusammenhang eine Vermittlung zwischen Polymeroberflächen und mineralischen Werkstoffen. T2 - HighTechMatBau CY - Berlin, Germany DA - 31.01.2018 KW - Zementgebundene Baustoffe KW - Lichtmikroskopie KW - Röntgen-3D-Computertomographie KW - Einzelfaserdurchzugsversuch KW - Windkanal KW - Fasermodifikation KW - Oberflächenfunktionalisierung KW - Grenzflächenaktive Verbindung PY - 2018 AN - OPUS4-44652 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giebson, C. A1 - Voland, K. A1 - Ludwig, H.-M. A1 - Meng, Birgit T1 - Alkali-silica reaction performance testing of concrete considering external alkalis and preexisting microcrack N2 - In concrete elements, simultaneously subjected to cyclic loadings and external alkalis, the risk for damage caused by or under participation of an alkali-silica reaction (ASR) is particularly high. This is of particular concern for concrete pavements due to the increasing heavy vehicle traffic and the application of sodium chloride (NaCl) de-icer during winter. Since 2004, the climate simulation concrete prism test (CS-CPT) has been used successfully to evaluate job mixtures for pavements by considering the impact of alkali-containing de-icers. However, the role of mechanical predamage on ASR is largely unclear. In a joint research project, the CS-CPT has been used to investigate the influence of preexisting microcracks on ASR. It was evident that an ASR initiated earlier in the predamaged concrete prisms due to the more rapid ingress of NaCl solution through the microcracks. KW - Alkali-silica reaction KW - Climate simulation concrete prism test KW - External alkalis KW - Laser-induced breakdown spectroscopy KW - Microcracks KW - Pavement concrete PY - 2017 DO - https://doi.org/10.1002/suco.201600173 SN - 1464-4177 SN - 1751-7648 VL - 18 IS - 4 SP - 528 EP - 538 PB - Ernst & Sohn AN - OPUS4-42574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stelzner, Ludwig A1 - Powierza, Bartosz A1 - Weise, Frank A1 - Oesch, Tyler A1 - Dlugosch, R. A1 - Meng, Birgit T1 - Analysis of moisture transport in unilateral-heated dense high-strength concrete N2 - Unilateral thermal exposure of concrete building components induces moisture transport processes that have a significant influence on the spalling behaviour of dense high-strength concrete (HSC). These transport processes are based on evaporation and condensation mechanisms of liquid and gaseous water in the pores as well as the chemically bound water within the concrete. The low permeability of HSC and the formation of a saturated zone within building components (also known as a moisture clog) leads to high water-vapour pressures, which contributes to explosive spalling. The formation of these pressures has already been verified by means of pore-pressure measurement techniques. In addition, the redistribution of the moisture within concrete specimens subject to unilateral thermal exposure has been demonstrated on fractured surfaces. Investigations by means of the nuclear magnetic resonance (NMR) relaxometry technique and neutron radiography have shown one-dimensional changes in moisture distribution during thermal exposure. However, none of these methods has been able to depict the moisture distribution in three dimensions (3D), so the link between pore size, concrete micro-structure and moisture content is missing. The research project presented in this paper aims to fill this gap by developing a new multi-level test methodology to characterise non-destructively the temporal course of spatial moisture distribution during unilateral thermal exposure. The procedure used during this programme included the collection of X-ray 3D-computed tomography (CT) measurements using a miniaturised specimen subjected to in-situ thermal exposure and the comparison of those CT results with the results of one-dimensional NMR-relaxometry before and after the heating process. In the first step, a mobile heating device was developed, built and tested. To simulate a unilaterally-heated construction component, a cylindrical specimen made of HSC (Ø = 40 mm, L = 100 mm) was cast into an impermeable glass ceramic shell. The ceramic shell ensured a one-dimensional moisture flux and limited the thermal expansion of the concrete. An additional high-temperature wool (HTW) insulating shell ensured a one-dimensional heat flux. The heating device, which operated using infrared radiation (IR), allowed the unilateral heating of the specimens up to 300 °C using variable heating regimes. In the second step, the mobile heating device was integrated into the CT-scanner, which enabled the collection of measurements before, during and after heating. By subtraction of successive 3D-CT images, X-ray attenuation differences could be resolved three-dimensionally in the specimen and interpreted as changes in the moisture content. Initial results show that this test methodology can monitor the 3D changes of moisture content inside the specimen during thermal exposure. It enables the researcher to visualise areas with moisture accumulation as well as dehydrated areas inside the specimen. Comparative one-dimensional NMR-relaxometry measurements confirm the results of the CT image analysis. T2 - 5th International Workshop on Concrete Spalling due to Fire Exposure CY - Boras, Sweden DA - 12.10.2017 KW - Spalling KW - Fire KW - Moisture clog KW - Moisture transport KW - HPC KW - HSC KW - X-ray CT KW - NMR KW - NDT PY - 2017 SN - 0284-5172 SP - 227 EP - 239 AN - OPUS4-42983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Meng, Birgit A1 - Weise, Frank A1 - Voland, K. A1 - Krütt, Enno T1 - Ermüdungsbedingte Degradation und ihre Auswirkungen auf den Stofftransport in Fahrbahndeckenbeton N2 - Im Rahmen des Beitrags soll aufgezeigt werden, welchen Einfluss eine mechanisch induzierte Vorschädigung (Ermüdungsbeanspruchung) auf den Ablauf und die Intensität des AKR-Schädigungsprozesses hat. Dies erfordert eine ausführliche Beschreibung der vielfältigen interagierenden Schädigungs- und Transportprozesse und aufbauend eine enge Verknüpfung von Experimenten mit einer mehrskaligen Modellierung. Die experimentelle Basis bildete die mechanische Vorschädigung (Ermüdungsbeansprochung) großformatiger Balken aus einem Fahrbahndeckenbeton bei Einsatz alkaliempfindlicher Gesteinskörnungen. Aus diesen großformatigen Balken wurden nach erfolgter Ermüdungsbeanspruchung kleinformatige Probekörper gewonnen. An diesen wurde detailliert untersucht wie sich die mechanische Vorschädigung auf das Betongefüge und die daraus resultierenden Transport- und Schädigungsprozesse auswirkt. Von der mechanisch induzierten Vorschädigung bis zum AKR Schädigungsprozess sollten in diesem Kontext die Rissbildungsprozesse und der interagierende Eintrag bzw. die Auslaugung der Alkalien ganzheitlich betrachtet werden. Der Beitrag fokussiert auf die Charakterisierung der infolge der mechanischen Vorschädigung induzierten Rissbildungsprozesse. Ferner wird detailliert auf die Auswirkungen der mechanischen Rissbildung auf den Stofftransport eingegangen. KW - Baustoffe KW - Beton KW - Dauerhaftigkeit KW - Ermüdung KW - Alkali-Kieselsäure-Reaktion KW - AKR PY - 2017 SN - 978-3-00-056692-9 SP - 416 EP - 427 CY - Bochum AN - OPUS4-42970 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Werder, Julia A1 - Simon, Sebastian A1 - Meng, Birgit T1 - Internal sulfate resistance of concrete N2 - If the amount of sulfate within the mix design for concrete is not balanced, ettringite formation which first controls solidification continues while the concrete is hardening. Ettringite forms by reaction of sulfate contained in the cement or in some admixture with calcium aluminate (C3A) as cement component. The “late primary ettringite formation” promotes an increase in volume within the hardened concrete leading to cracks. To analyze the effect of substituting part of ordinary Portland cement (OPC) by a treated brown coal fly ash mortar bars were tested according to ASTM C452. This test method was originally developed to extrapolate from the internal to external sulfate attack and is based on the idea that by testing a concrete mixture containing sulfate the process of deterioration is accelerated because it does not have to diffuse into the concrete before reaction first. In addition to the samples prescribed in ASTM C452 further samples in the size of the German SVA procedure were tested also designed for accessing the external sulfate resistance. The results show that while the replacement of 25 % of cement by brown coal fly ash leads to length changes around the limit defined by ASTM, the substitution of 50 % cement exceeded the limit by a multiple. The progress of expansion is the very similar for the two geometries tested. In-situ XRD measurements confirmed that while for pastes made of OPC the formation of ettringite is completed after 20 hours, this is not true for the mixtures containing the brown coal fly ash. In a different study the effect of hydrothermal treatment on the phase composition of ultra-high-performance concrete was analyzed. The results show that the sulfate and aluminate resulting from the decomposition of ettringite are bound into new phases. If this binding is permanent this might allow the larger use of sulfate bearing raw materials. T2 - EuroCoalAsh 2021 Conference CY - Online meeting DA - 02.11.2021 KW - Brown coal fly ash KW - Ettringite KW - Internal sulfate resistance KW - Test methods KW - In-situ XRD KW - Hydrothermal treatment PY - 2021 SP - 131 EP - 137 CY - Thessaloniki AN - OPUS4-54133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Meng, Birgit A1 - Müller, Urs A1 - Rübner, Katrin ED - Maierhofer, C. ED - Reinhardt, H.-W. ED - Dobmann, G. T1 - Components in concrete and their impact on quality: an overview KW - Concrete KW - Cement KW - Aggregate KW - Microstructure KW - Durability PY - 2010 SN - 978-1-84569-560-6 VL - 1 IS - Chapter 5 SP - 82 EP - 93 PB - Woodhead Publishing Ltd CY - Oxford AN - OPUS4-21049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Huismann, Sven A1 - Weise, Frank A1 - Meng, Birgit A1 - Schneider, U. ED - Kodur, V. ED - Franssen, J.-M. T1 - Influence of polypropylene fibres on the thermal strain of high strength concrete at high temperatures T2 - 6th International conference "Structures in fire" CY - East Lansing, Michigan, USA DA - 2010-06-02 KW - High performance concrete KW - High temperatures KW - Polypropylene fibres KW - Thermal strain KW - Acoustic emission KW - Ultrasound PY - 2010 SN - 978-1-60595-027-3 SP - 719 EP - 726 PB - DEStech Publications, Inc. CY - Lancaster, PA, USA AN - OPUS4-21563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Vasilic, Ksenija A1 - Roussel, N. A1 - Meng, Birgit A1 - Kühne, Hans-Carsten ED - Khayat, K.H. ED - Feys, D. T1 - Computational modeling of SCC flow through reinforced sections N2 - Computational modeling of fresh SCC flow is a comprehensive and time consuming task. The computational time is additionally increased when simulating casting of reinforced sections, where each single reinforcement bar has to be modeled. In order to deal with this issue and to decrease the computational time, an innovative approach of treating a reinforcement network as a porous medium is applied. This contribution presents the model for concrete flow through reinforced sections, based on Computational Fluid Dynamics (CFD), coupling a single-phase flow model for SCC and a continuum macroscopic model for porous medium. In the last part of this paper, numerical simulations are compared with experimental results obtained on model fluids. T2 - SCC2010 - Design, production and placement of self-consolidating concrete CY - Montreal, Canada DA - 2010-09-26 PY - 2010 SN - 978-90-481-9663-0 DO - https://doi.org/10.1007/978-90-481-9664-7_16 N1 - Serientitel: RILEM bookseries – Series title: RILEM bookseries VL - 1 IS - 5 SP - 187 EP - 195 PB - Springer AN - OPUS4-22277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Ramge, Peter A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Littmann, K. T1 - Parameterstudien zum Einfluss von Rezepturveränderungen auf Schwindverhalten, Rissneigung und Steifigkeit mineralischer Instandsetzungsmörtel T2 - 7. Internationales Kolloquium Industrieböden 2010 CY - Ostfildern, Deutschland DA - 2010-12-14 KW - Betoninstandsetzung KW - Instandsetzungsmörtel KW - Modulare Systeme KW - Haftverbund KW - SPCC KW - PCC PY - 2010 SN - 3-924813-85-X IS - Kap. 2.6 SP - 191 EP - 200 AN - OPUS4-22845 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramge, Peter A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Development of a modular system for the protection and repair of concrete structures KW - Repair mortar KW - Repair systems KW - Polymer cement concrete (PCC) KW - Sprayed polymer cement concrete (SPCC) PY - 2010 SN - 1864-7251 SN - 0947-4498 VL - 16 IS - 4/5 SP - 387 EP - 400 PB - Aedificatio Publ. CY - Freiburg AN - OPUS4-22773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Herbst, Tristan A1 - Hauer, B. A1 - Rübner, Katrin A1 - Meng, Birgit ED - Teipel, U. T1 - Wege zur Bewertung der Einsatzmöglichkeit sekundärer Gesteinskörnungen in Beton T2 - Symposium Rohstoffeffizienz und Rohstoffinnovationen CY - Nürnberg, Deutschland DA - 2010-02-04 KW - Gesteinskörnung KW - Beton KW - Nachhaltigkeit KW - Bewertung KW - Einsatzpotenzial PY - 2010 SN - 978-3-8396-0097-9 SP - 171 EP - 191 PB - Fraunhofer IRB Verl. AN - OPUS4-22952 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Herbst, Tristan A1 - Hauer, B. A1 - Rübner, Katrin A1 - Meng, Birgit T1 - Einsatzpotentzial und nachhaltige Verwertung von Hausmüllverbrennungsaschen als Gesteinskörnungen im Beton T2 - GDCh-Fachtagung Bauchemie 2009 CY - Freiberg, Deutschland DA - 2009-10-08 KW - Sekundärrohstoffe KW - Müllverbrennungsaschen KW - Sekundäre Gesteinskörnung PY - 2009 SN - 978-3-936028-61-4 VL - 41 SP - 237 EP - 240 AN - OPUS4-22951 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -